- Lanthanide(III) nitrobenzenesulfonates as new nitration catalysts: The role of the metal and of the counterion in the catalytic efficiency
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Lanthanide(III) complexes of p-nitrobenzenesulfonic acid, Ln(p-NBSA) 3, m-nitrobenzenesulfonic acid, Ln(m-NBSA)3, and 2,4-nitrobenzenesulfonic acid, Ln(2,4-NBSA)3, were prepared, characterized and examined as catalyst for the nitration of benzene, toluene, xylenes, naphthalene, bromobenzene and chlorobenzene. The initial screening of the catalysts showed that lanthanum(III) complexes were more effective than the corresponding ytterbium(III) complexes, and that catalysts containing the bulky 2,4-NBSA ligand were less effective than the catalyst containing p-NBSA (nosylate) or m-NBSA ligands. Examination of a series of Ln(p-NBSA)3 and Ln(m-NBSA)3 catalysts revealed that there is a clear correlation between the ionic radii of the lanthanide(III) ions and the yields of nitration, with the lighter lanthanides being more effective. The X-ray single crystal structure of Yb(m-NBSA)3·6H2O shows that two m-NBSA ligands are directly bound to the metal centre while the third ligand is not located in the first coordination sphere, but it is hydrogen bonded to one of the water molecules which is coordinated to ytterbium(III). NMR studies suggest that this structure is preserved under the conditions used in the nitration reaction. The structure of Yb(m-NBSA)3 is markedly different from the structure of the well-known ytterbium(III) triflate catalyst. The coordination of the nitrobenzenesulfonate counterion to the lanthanide(III) ion suggests that steric effects might play an important role in determining the efficiency of these novel nitration catalysts. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Parac-Vogt, Tatjana N.,Pachini, Sophia,Nockemann, Peter,Van Hecke, Kristof,Van Meervelt, Luc,Binnemans, Koen
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- Catalysis of Nitration of Naphthalene by Lower Oxides of Nitrogen
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Nitrous acid catalyzed nitration of naphthalene does not proceed through nitrosation, and the mechanism is best understood in terms of a chain reaction involving naphthalene radical cation.
- Ross, David S.,Moran, Kelly D.,Malhotra, Ripudaman
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- Competitive Reactions of Trinitromethanide Ion and Nitrogen Dioxide with Radical Cations
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From the species generated by photoexcitation of ArH-tetranitromethane charge transfer complexes, ArH radical cation, trinitromethanide ion and nitrogen dioxide, the reaction between ArH radical cation and trinitromethanide has been shown to be significantly faster than that between ArH radical cation and nitrogen dioxide.
- Eberson, Lennart,Hartshorn, Michael P.,Svensson, Jan O.
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- Zeolite-assisted regioselective mononitration of naphthalene with nitrogen dioxide/molecular oxygen
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The nitration process using nitrogen dioxide and oxygen instead of the classical nitric acid-sulfuric acid system appears to be attractive and promising in the selective preparation of nitro compounds. The ratio of 1-nitronaphthalene isomer to 2-nitronaphthalene can reach 11 in a moderate yield of 60 % when the reaction is carried out in acetonitrile with 5.0 mmol naphthalene, 10 mmol nitrogen dioxide, and 0.13 g HZSM-5 under molecular oxygen atmosphere at -15 C. The isomeric distribution of the product nitro-naphthalene was found to be superior to traditional methods. The zeolite could be easily regenerated and recycled and reused by simple work-up to give results similar to those obtained with the fresh catalyst.
- Shi, Chunjie,Peng, Xinhua,Tai, Yanfang,Dong, Xiongzi,Wang, Haocai
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- Zeolite-assisted regioselective synthesis of dinitronaphthalene
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The nitration selectivity of naphthalene was studied in different organic solvents with 95 % fuming nitric acid as nitration reagent. The yield of dinitronaphthalene can achieve 78 % in hexane. With nitrogen dioxide as nitration reagent in oxygen, the selectivity of dinitronaphthalene in different types of molecular sieve catalyst was studied. When HBEA zeolite catalyst was used, the yield of dinitronaphthalene was up to 61 %. This method is easy to carry out, environmentally benign, and economical.
- Wang, Haocai,Peng, Xinhua,Shi, Chunjie,Dong, Xiongzi,Tai, Yanfang,Liu, Hongtao
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- NO2+ nitration mechanism of aromatic compounds: Electrophilic vs charge-transfer process
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The nitration of methylnaphthalenes with NO2BF4 and NOBF4 was examined in order to shed light on the controversial aromatic nitration mechanism, electrophilic vs charge-transfer process. The NO2+ nitration of 1,8-dimethylnaphthalene showed a drastic regioselectivity change depending on the reaction temperature, where ortho-regioselectivity at -78 °C and para- regioselectivity at 0 °C were considered to reflect the electrophilic and the direct or alternative charge-transfer process, respectively, because the NO+ nitration through the same reaction intermediates as in the NO2+ nitration via a charge-transfer process resulted in para-regioselectivity regardless of the reaction temperature. The NO2+ nitration of redox potential methylnaphthalenes higher than 1,8-dimethylnaphthalene gave a similar ortho-regioselectivity enhancement to 1,8-dimethylnaphthalene at lower temperature, thus reflecting the electrophilic process. On the other hand, the NO2+ nitration of redox potential methylnaphthalenes lower than 1,8-dimethylnaphthalene showed para-regioselectivity similar to the NO+ nitration, indicating the direct or alternative charge-transfer process. In the presence of strong acids where the direct charge-transfer process will be suppressed by protonation, the ortho-regioselectivity enhancement was observed in the NO2+ nitration of 1,8-dimethylnaphthalene, suggesting that the direct charge-transfer process could be the main process to show para- regioselectivity. These experimental results imply that the NO2+ nitration proceeds via not only electrophilic but also direct charge-transfer processes, which has been considered to be unlikely because of the high energy demanding process of a bond coordination change between NO2+ and NO2. Theoretical studies at the MP2/6-31G(d) level predicted ortho- and para-regioselectivity for the NO2+ nitration via electrophilic and charge- transfer processes, respectively, and the preference of the direct charge- transfer process over the alternative one, which support the experimental conclusion.
- Tanaka, Mutsuo,Muro, Eiko,Ando, Hisanori,Xu, Qiang,Fujiwara, Masahiro,Souma, Yoshie,Yamaguchi, Yoichi
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- Photochemical Nitration by Tetranitromethane. Part XIX. The Competitive Reactions of Trinitromethanide and Nitrogen Dioxide with Radical Cations and their Use for Selective Nitrations
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The photolysis of the charge-transfer complex between an aromatic compound (ArH) and tetranitromethane is known to form initially a triad of the aromatic radical cation, trinitromethanide ion and NO2 .For reactive and moderately reactive radical cations, the chemical follow-up ion and (i) reactions from the species of the triad are fast at -60 deg C, as shown by the fact that the solutions are EPR-silent during photolysis.However, by conducting the photolysis in the presence of a protic acid, the trinitromethanide ion is rendered unreactive by protonation, resulting in the build-up of a detectable (EPR) concentration of ArH-radical cation or (ArH)2-radical cation.This shows that the initial chemical step from the triad is the nucleophilic attack of trinitromethanide ion upon ArH-radical cation, and that the rate of the reaction between the latter and NO2 must be significantly lower.Preparative experiments support this conclusion, in that the predominant adduct formation from ArH-tetranitromethane photolysis is diverted into nitro substitution in the presence of a protic acid, the latter reaction occurring via ArH-radical cation-NO2 coupling.These findings also establish that results obtained from the photonitration of aromatics by tetranitromethane are not relevant for judging the possible electron transfer nature of electrophilic aromatic nitration by nitronium ion.
- Eberson, Lennart,Hartshorn, Michael P.,Radner, Finn,Svensson, Jan O.
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- The polyhedral nature of selenium-catalysed reactions: Se(iv) species instead of Se(vi) species make the difference in the on water selenium-mediated oxidation of arylamines
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Selenium-catalysed oxidations are highly sought after in organic synthesis and biology. Herein, we report our studies on the on water selenium mediated oxidation of anilines. In the presence of diphenyl diselenide or benzeneseleninic acid, anilines react with hydrogen peroxide, providing direct and selective access to nitroarenes. On the other hand, the use of selenium dioxide or sodium selenite leads to azoxyarenes. Careful mechanistic analysis and 77Se NMR studies revealed that only Se(iv) species, such as benzeneperoxyseleninic acid, are the active oxidants involved in the catalytic cycle operating in water and leading to nitroarenes. While other selenium-catalysed oxidations occurring in organic solvents have been recently demonstrated to proceed through Se(vi) key intermediates, the on water oxidation of anilines to nitroarenes does not. These findings shed new light on the multifaceted nature of organoselenium-catalysed transformations and open new directions to exploit selenium-based catalysis.
- Capperucci, Antonella,Dalia, Camilla,Tanini, Damiano
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supporting information
p. 5680 - 5686
(2021/08/16)
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- Photoinduced Iron-Catalyzed ipso-Nitration of Aryl Halides via Single-Electron Transfer
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A photoinduced iron-catalyzed ipso-nitration of aryl halides with KNO2 has been developed, in which aryl iodides, bromides, and some of aryl chlorides are feasible. The mechanism investigations show that the in situ formed iron complex by FeSO4, KNO2, and 1,10-phenanthroline acts as the light-harvesting photocatalyst with a longer lifetime of the excited state, and the reaction undergoes a photoinduced single-electron transfer (SET) process. This work represents an example for the photoinduced iron-catalyzed Ullmann-type couplings.
- Wu, Cunluo,Bian, Qilong,Ding, Tao,Tang, Mingming,Zhang, Wenkai,Xu, Yuanqing,Liu, Baoying,Xu, Hao,Li, Hai-Bei,Fu, Hua
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p. 9561 - 9568
(2021/08/06)
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- N-Nitroheterocycles: Bench-Stable Organic Reagents for Catalytic Ipso-Nitration of Aryl- And Heteroarylboronic Acids
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Photocatalytic and metal-free protocols to access various aromatic and heteroaromatic nitro compounds through ipso-nitration of readily available boronic acid derivatives were developed using non-metal-based, bench-stable, and recyclable nitrating reagents. These methods are operationally simple, mild, regioselective, and possess excellent functional group compatibility, delivering desired products in up to 99% yield.
- Budinská, Alena,Katayev, Dmitry,Passera, Alessandro,Zhang, Kun
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supporting information
(2020/03/30)
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- Bismuth nitrate as a source of nitro radical in ipso-nitration of carboxylic acids
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Aromatic nitro compounds are extensively used in synthetic chemistry. We disclose a new approach to obtain nitroarenes regioselectively starting from carboxylic acids under acid-free reaction conditions.
- Agasti, Soumitra,Maiti, Siddhartha,Maity, Soham,Anniyappan,Talawar,Maiti, Debabrata
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p. 120 - 124
(2019/05/22)
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- Silica-supported perchloric acid and potassium bisulfate as reusable green catalysts for nitration of aromatics under solvent-free microwave conditions
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Silica-supported perchloric acid and bisulfate (SiO2/HClO4 and SiO2/KHSO4) have been developed as reusable green catalysts for nitration of aromatic compounds using NaNO2 in acetonitrile medium under conventional and solvent-free microwave conditions. The reaction times under microwave irradiation are significantly shorter than conventional method even though the yields obtained in microwave-assisted reactions are comparable with those obtained under reflux conditions.
- Kumar, M. Satish,Sriram, Y. Hemanth,Venkateswarlu,Rajanna,Sudhakar, M. Sai,Venkanna, Purugula,Saiprakash
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supporting information
p. 59 - 67
(2017/12/26)
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- Method for preparing nitro compound by using graphene to catalyze carbon dioxide
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The invention discloses a method for preparing a nitro compound by using graphene to catalyze carbon dioxide. A graphene material is applied to catalysis of a reaction of carbon dioxide and a nitrification substrate such as an aromatic compound to prepare the nitro compound. The method is used for replacing a traditional nitric acid/sulfur acid method to prepare the nitro compound, so that the atom utilization rate of the reaction is increased, the energy is saved, and the emission is reduced; and the method has the characteristic of atom economy during industrial preparation of the nitro compound.
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Paragraph 0035-0036
(2018/06/16)
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- Method for preparing nitro compound by using graphene to catalyze nitric oxide
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The invention discloses a method for preparing a nitro compound by using graphene to catalyze nitric oxide. A graphene oxide carbon material is used for catalysis of a reaction of nitric oxide and a nitrification substrate such as an aromatic compound to prepare the nitro compound. The method is used for replacing a traditional nitric acid/sulfur acid method to prepare the nitro compound, so thatthe atom utilization rate of the reaction is increased, the energy is saved, and the emission is reduced; and the method has the characteristic of atom economy during industrial preparation of the nitro compound.
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Paragraph 0039; 0040
(2018/06/16)
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- Organocatalytic oxidation of substituted anilines to azoxybenzenes and nitro compounds: Mechanistic studies excluding the involvement of a dioxirane intermediate
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An organocatalytic and environmentally friendly approach for the selective oxidation of substituted anilines was developed. Utilizing a 2,2,2-trifluoroacetophenone-mediated oxidation process, substituted anilines can be transformed into azoxybenzenes, while a simple treatment with MeCN and H2O2 leads to the corresponding nitro compounds, providing user-friendly protocols that can be easily scaled up. Various substitution patterns and functional groups were tolerated leading to products in high to excellent yields. Mechanistic studies utilizing HRMS provide clear evidence for the distinct mechanistic intermediates that are involved. This study constitutes an indirect proof excluding the involvement of a dioxirane intermediate in the green organocatalytic oxidation, utilizing 2,2,2-trifluoroacetophenone as the catalyst.
- Voutyritsa, Errika,Theodorou, Alexis,Kokotou, Maroula G.,Kokotos, Christoforos G.
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supporting information
p. 1291 - 1298
(2017/06/06)
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- Convenient, metal-free ipso-nitration of arylboronic acids using nitric acid and trifluoroacetic acid
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A feasible protocol for the direct ipso-nitration of arylboronic acids using trifluoroacetic acid and nitric acid as nitration reagent has been developed. Various aromatic nitro compounds are produced in moderate to good yields under the metal-free conditions. The method is operationally simple and regioselective, and might have potential application in industry.
- Shen, Guodong,Zhao, Lingyu,Liu, Wanxing,Huang, Xianqiang,Song, Huina,Zhang, Tongxin
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supporting information
p. 10 - 14
(2016/12/30)
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- Nucleophilic Nitration of Arynes by Sodium Nitrite and its Multicomponent Reaction Leading to Double-Functionalized Arenes
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An unusual nucleophilic nitration of arynes by NaNO2 in the presence of water has been developed, and the concept was further demonstrated to accomplish a double functionalization of arynes using a multicomponent reaction protocol to synthesize pharmaceutically important (2-nitrophenyl)methanol derivatives. Such substitution ortho to -NO2 is difficult by other means. The reaction conditions are mild and avoid the use of strong acids, expensive transition metal catalysts, and additives.
- Dhokale, Ranjeet A.,Mhaske, Santosh B.
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supporting information
p. 3010 - 3013
(2016/07/06)
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- Enhancing the photocatalytic activity of GaN by electrochemical etching
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Nanoporous (NP) GaN thin films prepared with electrochemical etching method were investigated as photocatalysts in dye photodegradation systematically. The comparison of NP GaN thin films with GaN thin films showed that NP GaN thin films with high surface
- Cao, Dezhong,Xiao, Hongdi,Xu, Hangzhou,Cui, Jishi,Gao, Qingxue,Pei, Haiyan
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p. 881 - 886
(2015/07/01)
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- Phosphoric acid modified montmorillonite clay: A new heterogeneous catalyst for nitration of arenes
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The easily available montmorillonite clay is treated with phosphoric acid and 10 wt.% is found to be the optimum concentration of phosphoric acid that can be adsorbed chemically on the surface of the clay. Acidity of this phosphoric acid treated montmorillonite clay (PAM) is determined by volumetric as well as potentiometric titration and characterized. Catalytic efficacy of PAM in nitration of various aromatic compounds is reported.
- Bharadwaj, Saitanya K.,Boruah, Purna K.,Gogoi, Pradip K.
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p. 124 - 128
(2014/12/11)
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- Catalytic asymmetric benzidine rearrangement
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A chiral Br?nsted acid catalyzes the asymmetric benzidine rearrangement of N,N′-dinaphthylhydrazines. Different electronically and structurally diverse axially chiral 2,2′-binaphthyl diamine (BINAM) derivatives are obtained with high enantioselectivity. Copyright
- De, Chandra Kanta,Pesciaioli, Fabio,List, Benjamin
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p. 9293 - 9295
(2013/09/12)
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- Copper MOF: Scope and limitation in catalytic hydroxylation and nitration of aryl halides
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The potential catalytic application of MOFs like [Cu3(btc) 2] (btc=1,3,5-benzenetricarboxylate), [Cu(bdc)] (bdc=1,4- benzenedicarboxylate), [Cu(pymo)2] (pymo=2-hydroxypyrimidinalote) and [Cu(im)2] (im=imidazolate) was explored in the hydroxylation and nitration of aryl halides. Cu3(btc)2 was found to be superior for both the reactions furnishing good to excellent yields of the respective products. The studies demonstrated that MOFs are not recyclable, attributable to their instability in the highly polar and basic conditions demanded for these reactions. Complete transformation of MOFs to copper oxide nanoparticles occurred in hydroxylation, whereas significant alteration in frameworks was observed for the recovered catalyst in nitration.
- Priyadarshini,Amal Joseph,Kantam, M. Lakshmi,Sreedhar
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p. 6409 - 6414
(2013/07/26)
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- Zeolite-assisted regioselective synthesis of dinitronaphthalene
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Efficient methods of nitration of naphthalene or 1-nitronaphthalane with fuming nitric acid (wt. 95 %) in organic solvent over zeolite were investigated, where the regioselection of nitration can be improved and in certain cases the isomer ratio of nitration products can be reversed. The recovered zeolite was reused three times without appreciable loss of catalytic activity.
- Shi, Wenwen,Peng, Xinhua,Dong, Xiongzi,Wang, Haocai,Shi, Chunjie
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experimental part
p. 4975 - 4978
(2012/10/08)
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- Copper-catalyzed nitration of arylboronic acids with nitrite salts under mild conditions: An efficient synthesis of nitroaromatics
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Copper-catalyzed nitration of arylboronic acids has been developed with nitrite salts as nitrating agent under mild conditions. This process provides an efficient and practical method for the synthesis of nitro aromatics, due to its simple experimental procedure and its use of convenient and inexpensive copper catalyst.
- Yan, Guobing,Zhang, Ling,Yu, Jian
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experimental part
p. 133 - 137
(2012/07/28)
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- Ipso-nitration of arylboronic acids with bismuth nitrate and perdisulfate
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An efficient and one pot synthetic method of ipso-nitration of arylboronic acids has been developed. The high efficiency, general applicability, and broader substrate scope including heterocycles and functional groups make this method advantageous. Due to its simplicity, we expect to find application of this method in synthesis.
- Manna, Srimanta,Maity, Soham,Rana, Sujoy,Agasti, Soumitra,Maiti, Debabrata
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supporting information; experimental part
p. 1736 - 1739
(2012/05/20)
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- Catalyst-free ipso-nitration of aryl boronic acids using bismuth nitrate
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We report a catalyst-free ipso-nitration of aryl boronic acids using bismuth (III) nitrate as nitrating agent. Reaction proceeds in shorter reaction times with moderate to excellent yields. This method is operationally simple, regioselective, and possesses excellent functional group compatibility to synthesize nitroarenes.
- Yadav, Rammohan R.,Vishwakarma, Ram A.,Bharate, Sandip B.
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supporting information
p. 5958 - 5960,3
(2020/07/31)
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- Green and controllable metal-free nitrification and nitration of arylboronic acids
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A novel and green nitrating reagent has been developed for the nitrification and nitration of arylboronic acids, which can be controlled by the reaction conditions. The process provides an attractive alternative to the traditional nitration protocols.
- Wang, Shuai,Shu, Chun Chun,Wang, Tao,Yu, Jian,Yan, Guo Bing
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scheme or table
p. 643 - 646
(2012/08/07)
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- Copper catalyzed ipso-nitration of iodoarenes, bromoarenes and heterocyclic haloarenes under ligand-free conditions
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A catalytic protocol for the conversion of haloarenes into the corresponding nitroarenes is presented using copper salts under ligand-free conditions. The method was effectively utilized for the ipso-nitration of a broad variety of haloarenes that includes iodoarenes, bromoarenes, and heterocyclic haloarenes.
- Amal Joseph,Priyadarshini,Lakshmi Kantam,Maheswaran
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supporting information; experimental part
p. 1511 - 1513
(2012/03/27)
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- Convenient and mild synthesis of nitroarenes by metal-free nitration of arylboronic acids
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A novel methodology for the direct nitration of arylboronic acids has been developed. By using inexpensive tert-butyl nitrite various aromatic nitro compounds are produced in moderate to good yields (45-87%) without the need of any catalyst.
- Wu, Xiao-Feng,Schranck, Johannes,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 12462+12463
(2012/02/03)
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- Pd-catalyzed conversion of aryl chlorides, triflates, and nonaflates to nitroaromatics
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(Chemical Equation Presented) An efficient Pd catalyst for the transformation of aryl chlorides, triflates, and nonaflates to nitroaromatics has been developed. This reaction proceeds under weakly basic conditions and displays a broad scope and excellent
- Fors, Brett P.,Buchwald, Stephen L.
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supporting information; experimental part
p. 12898 - 12899
(2009/12/07)
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- Ceric ammonium nitrate (CAN) as oxidizing or nitrating reagent for organic reactions in ionic liquids
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The reaction of ceric ammonium nitrate, (NH4)2[Ce(NO3)6] or CAN, with naphthalene and 2-methylnaphthalene in the ionic liquid 1-ethyl-3-methylimidazolium triflate showed that the reaction products are strongly d
- Deleersnyder, Karen,Schaltin, Stijn,Fransaer, Jan,Binnemans, Koen,Parac-Vogt, Tatjana N.
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scheme or table
p. 4582 - 4586
(2009/10/11)
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- LIGANDS FOR TRANSITION-METAL-CATALYZED CROSS-COUPLINGS, AND METHODS OF USE THEREOF
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Ligands for transition metals are disclosed herein, which may be used in various transition-metal-catalyzed carbon-heteroatom and carbon-carbon bond-forming reactions. The disclosed methods provide improvements in many features of the transition-metal-catalyzed reactions, including the range of suitable substrates, number of catalyst turnovers, reaction conditions, and efficiency. For example, improvements have been realized in transition-metal-catalyzed cross-coupling reactions.
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Page/Page column 144-145
(2009/07/17)
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- Nitration of aromatic compounds catalyzed by divanadium-substituted molybdophosphoric acid, H5[PMo10V2O 40]
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The nitration of aromatic compounds was carried out in the presence of divanadium-substituted molybdophosphoric acid, H5PMo 10V2O40, as catalyst and a mixture of nitric acid and acetic anhydride as nitrating agent. In the presence of this heteropolyacid the ortho- and para-nitro compounds were obtained in good to excellent yields under mild reaction conditions. Springer-Verlag 2007.
- Heravi, Majid M.,Bakhtiari, Khadijeh,Benmorad, Tina,Bamoharram, Fatemeh F.,Oskooie, Hossein A.,Tehrani, Maryam H.
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p. 449 - 452
(2008/02/02)
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- Imidazolium ionic liquids as solvents for cerium(IV)-mediated oxidation reactions
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Use of imidazolium ionic liquids as solvents for organic transformations with tetravalent cerium salts as oxidizing agents was evaluated. Good solubility was found for ammonium hexanitratocerate(IV) (ceric ammonium nitrate, CAN) and cerium(IV) triflate in 1-alkyl-3-methylimidazolium triflate ionic liquids. Oxidation of benzyl alcohol to benzaldehyde in 1-ethyl-3-methylimidazolium triflate was studied by in-situ FTIR spectroscopy and 13C NMR spectroscopy on carbon-13-labeled benzyl alcohol. Careful control of the reaction conditions is necessary because ammonium hexanitratocerate(IV) dissolved in an ionic liquid can transform benzyl alcohol not only into benzaldehyde but also into benzyl nitrate or benzoic acid. The selectivity of the reaction of cerium(IV) triflate with benzyl alcohol in dry ionic liquids depends on the degree of hydration of cerium(IV) triflate: anhydrous cerium(IV) triflate transforms benzyl alcohol into dibenzyl ether, whereas hydrated cerium(IV) triflate affords benzaldehyde as the main reaction product. Reactions of ammonium hexanitratocerate(IV) with organic substrates other than benzyl alcohol have been explored. 1,4-Hydroquinone is quantitatively transformed into 1,4-quinone. Anisole and naphthalene are nitrated. For the cerium-mediated oxidation reactions in ionic liquids, high reaction temperatures are an advantage because under these conditions smaller amounts of byproducts are formed.
- Mehdi, Hasan,Bodor, Andrea,Lantos, Diana,Horvath, Istvan T.,De Vos, Dirk E.,Binnemans, Koen
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p. 517 - 524
(2007/10/03)
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- Formation of arenes via diallylarenes: Strategic utilization of Suzuki-Miyaura cross-coupling, Claisen rearrangement and ring-closing metathesis
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Two new synthetic strategies for benzoannulation are reported. The first strategy is based on the Suzuki-Miyaura cross-coupling reaction. To this end, various ortho-diallylbenzene derivatives were prepared from the corrresponding diiodo derivatives by an allylation strategy using an allylboronate as coupling partner. These diallyl derivatives were subjected to a ring-closing metathesis (RCM) and one-pot dichlorodicyanoquinone (DDQ) oxidation sequence to deliver 2-substituted naphthalenes. In the second strategy, a double Claisen rearrangement and RCM protocol have been used as key steps to give highly functionalized benzoannulated quinone derivatives.
- Kotha, Sambasivarao,Shah, Vrajesh R.,Mandal, Kalyaneswar
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p. 1159 - 1172
(2008/04/03)
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- Ortho effect in the Bergman cyclization: Comparison of experimental approaches and dissection of cycloaromatization kinetics
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Four different experimental sources of kinetic information were combined to study the effect of ortho substituents on the rate of Bergman cycloaromatization. All methods confirm that the cyclization barrier is highly sensitive to the nature of the ortho substituents. However, the measured activation energies strongly depend on the choice of experimental technique: even the relative trends provided by the different methods agree with each other only in the case of acceptor substituents. Both the onset peaks and the activation energies determined by differential scanning calorimetry (DSC; either in neat enediynes or in their solutions in 10.6 M 1,4-cyclohexadiene (1,4-CHD)) strongly overestimate the reactivity of 1,2-diethynylbenzene, suggesting that DSC cannot be taken as a reliable indicator of enediyne reactivity. This discrepancy is likely to stem from the presence of side reactions with low activation barriers, especially important when the reaction is conducted in neat enediyne. On the other hand, kinetic measurements based on monitoring the concentrations of enediyne reactants and naphthalene products provide reliable general trends that include the parent benzannelated enediyne. These measurements confirm that both ortho-NO2 and ortho-CHO substituents substantially decrease activation energies for the Bergman cyclization, supporting earlier computational predictions. A comparison of theory and experiment suggests that computations at the Moeller-Plesset second-order perturbation theory (MP2)/6-31G** level provide an excellent alternative to DFT when an accurate description of the contribution of noncovalent interactions to the activation energy is needed. Activation energies derived from keff, the effective rate constant under the pseudo-first-order approximation, depend on the 1,4-CHD concentrations. The true rate constant, k-1, for the cyclization step and the ratio of constants for the retro-Bergman ring opening, k-1, and the intermolecular H-atom abstraction, k2, were determined from the dependence of cycloaromatization kinetics of ortho- and para-NO2 substituted enediynes on the concentration of 1,4-CHD.
- Zeidan, Tarek A.,Kovalenko, Serguei V.,Manoharan, Mariappan,Alabugin, Igor V.
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p. 962 - 975
(2007/10/03)
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- From β-nitrothiophenes to ring-fused nitrobenzenes: An overall ring-enlargement process via a facile, aromatization-driven, thermal 6π electrocyclization
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In prosecution of previous work on the thermal cyclization of 1-aryl-4-methanesulfonyl-2-nitro-3-phenylsulfonyl-1,3-butadienes (7), the 3-unsubstituted derivatives 8, deriving from the initial ring opening of 3-nitrothiophene (2), have been likewise found herein to undergo cyclization, followed by aromatization, in analogous mild experimental conditions, leading to the ring-fused homo- or heteroaromatic nitro derivatives 10. The concerted electrocyclic nature of the process is strongly supported by the outcome of tests based on the variation of the polarity of the solvent or of the electron density on the aryl of 8. Thus, the successful application of the process to the non-phenylsulfonyl-activated 8 significantly widens the scope of a synthetically valuable overall ring-opening/ring-closing procedure from nitrothiophenes. Support to the recently renewed interest in thermal 6π electrocyclizations as a tool for the construction of the benzene ring is furthermore provided.
- Bianchi, Lara,Dell'Erba, Carlo,Maccagno, Massimo,Petrillo, Giovanni,Rizzato, Egon,Sancassan, Fernando,Severi, Elda,Tavani, Cinzia
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p. 8734 - 8738
(2007/10/03)
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- A convenient method for the oxidation of aromatic amines to nitro compounds using tetra-n-alkylammonium bromates
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Tetra-n-propyl and tetra-n-butylammonium bromates were used for the oxidation of a variety of aromatic amines to nitro compounds. Reaction condition and recovery simple and yield of products high.
- Das, Satya Sandhya,Nath, Utpal,Deb, Dibakar,Das, Pranab J.
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p. 2359 - 2363
(2007/10/03)
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- Lanthanide(III) nosylates as new nitration catalysts
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Lanthanide(III) nosylates are novel, recyclable catalysts prepared from the noncorrosive and inexpensive p-nitrotoluenesulfonic acid and the corresponding lanthanide(III) oxide. With 5-10% catalyst loading, atom economic nitration of simple aromatic compounds was achieved in good to high yields.
- Parac-Vogt, Tatjana N.,Binnemans, Koen
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p. 3137 - 3139
(2007/10/03)
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- Electrophilic nitration of aromatics in ionic liquid solvents
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Potential utility of a series of 1-ethyl-3-methylimidazolium salts [emim][X] with X = OTf-, CF3COO-, and NO3- as well as [HNEtPri2][CF3COO] (protonated Huenig's base) ionic liquids were explored as solvent for electrophilic nitration of aromatics using a variety of nitrating systems, namely NH4NO3/TFAA, isoamyl nitrate/BF3·Et2O, isoamyl nitrate/TfOH, Cu(NO3)/TFAA, and AgNO3/Tf2O. Among these, NH4NO3/TFAA (with [emim][CF3COO], [emim][NO3]) and isoamyl nitrate/BF3·Et2O, isoamyl nitrate/TfOH (with [emim][OTf]) provided the best overall systems both in terms of nitration efficiency and recycling/reuse of the ionic liquids. For [NO2][BF4] nitration, the commonly used ionic liquids [emim][AlCl4] and [emim][Al2Cl7] are unsuitable, as counterion exchange and arene nitration compete. [Emim][BF4] is ring nitrated with [NO2][BF4] producing [NO2-emim][BF4] salt, which is of limited utility due to its increased viscosity. Nitration in ionic liquids is surveyed using a host of aromatic substrates with varied reactivities. The preparative scope of the ionic liquids was also extended. Counterion dependency of the NMR spectra of the [emim][X] liquids can be used to gauge counterion exchange (metathesis) during nitration. Ionic liquid nitration is a useful alternative to classical nitration routes due to easier product isolation and recovery of the ionic liquid solvent, and because it avoids problems associated with neutralization of large quantities of strong acid.
- Laali,Gettwert
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- Linear free energy relationships in the Bergman cyclization of 4-substituted-1,2-diethynylbenzenes
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A series of 4-substituted-1,2-diethylnylbenzenes were prepared (1a-f) and subjected to Bergman cyclization. Bulk cyclization proceeded to produce the corresponding 2-substituted naphthalenes (2a-f) in good yields (59-78%). Kinetic experiments show a linear free energy relationship between the cyclization rate and the Hammett σ(m) substituent coefficient and the Swain-Lupton field and resonance parameters. (C) 2000 Elsevier Science Ltd.
- Choy,Kim,Ballestero,Artigas,Diez,Lichtenberger,Shapiro,Russell
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p. 6955 - 6958
(2007/10/03)
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- Nitration of polycyclic aromatic hydrocarbons using a supported catalyst
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We report the use of a catalyst, sulfuric acid supported on silica-gel, as a promising method for facile, high yielding, regioselective syntheses of mononitrated polycyclic aromatic hydrocarbons, 6-nitrochrysene, 1- nitropyrene, 1-nitronaphthalene, 2-nitrofluorene, 3-nitrofluoranthene, and 9- nitroanthracene.
- Smith, Amy C.,Narvaez, Lorena D.,Akins, Bridget G.,Langford, Moses M.,Gary, Thomas,Geisler, Victoria J.,Khan, Farooq A.
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p. 4187 - 4192
(2007/10/03)
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- Lanthanide(III) triflates as recyclable catalysts for atom economic aromatic nitration
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Lanthanide(III) triflates catalyse (1-10 mol%) the nitration of a range of simple aromatic compounds in good to excellent yield using stoichiometric quantities of 69% nitric acid; the only by-product is water and the catalyst can be readily recycled by simple evaporation.
- Waller, Francis J.,Barrett, Anthony G. M.,Braddock, D. Christopher,Ramprasad, Dorai
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p. 613 - 614
(2007/10/03)
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- Iron(III)-catalysed nitration of non-activated and moderately activated arenes with nitrogen dioxide-molecular oxygen under neutral conditions
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In the presence of molecular oxygen and a catalytic amount of tris(pentane-2,4-dionato)iron(III), non-activated and moderately activated arenes, which include alkylbenzenes, halogenobenzenes, phenolic ethers, naphthalene and derivatives, can be nitrated with nitrogen dioxide at ice-bath temperature or below to give the corresponding nitro derivatives in fair to good yields. An electron-transfer mechanism has been proposed, where an activated NO2-FeIII complex plays a key role in the cyclic process for converting arenes into nitroarenes.
- Suzuki, Hitomi,Yonezawa, Shuji,Nonoyama, Nobuaki,Mori, Tadashi
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p. 2385 - 2389
(2007/10/03)
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- Method for preparing aromatic secondary amino compound
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Disclosed are (1) a method for preparing an aromatic secondary amino compound which comprises reacting an N-cyclohexylideneamino compound in the presence of a hydrogen moving catalyst and a hydrogen acceptor by the use of a sulfur-free polar solvent and/or a cocatalyst, and (2) a method for preparing an aromatic secondary amino compound which comprises reacting cyclohexanone or a nucleus-substituted cyclohexanone, an amine and a nitro compound corresponding to the amine in a sulfur-free polar solvent in the presence of a hydrogen moving catalyst, a cocatalyst being added or not added. In a further aspect, a method is provided for the preparation of aminodiphenylamine by reacting phenylenediamine and cyclohexanone in the presence of a hydrogen transfer catalyst in a sulfur-free polar solvent while using nitroaniline as a hydrogen acceptor.
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- Ozone-mediated nitration of naphthalene and some methyl derivatives with nitrogen dioxide. Remarkable enhancement of the 1-nitro/2-nitro isomer ratio and mechanistic implications
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Naphthalene, 1- and 2-methylnaphthalenes were smoothly nitrated with nitrogen dioxide at low temperatures in the presence of ozone to afford the corresponding nitro derivatives in high yields.For naphthalene, the 1-nitro/2-nitro isomer ratios were remarkably high, mostly ranging from 35 to 70. 1,4-Dimethylnaphthalene suffered extensive side-chain substitution under similar conditions.The enhanced regioselectivity as compared with conventional nitrations has been interpreted in terms of the electron transfer mechanism involving the nitrogen trioxide as the initial electrophile.
- Suzzuki, Hitomi,Mori, Tadashi
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p. 677 - 684
(2007/10/03)
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- NAPHTHALENE NITRATION IN THE PRESENCE OF ZEOLITES
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The degree of naphthalene conversion in its nitration with 70percent nitric acid, catalyzed by erionite, ZSM-5, ZSM-11, ZSM-12, and Beta zeolites, has been determined.
- Bakhvalov, O. V.,Ione, K. G.
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- Electron Affinities of Naphthalene, Anthracene and Substituted Naphthalenes and Anthracenes
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The determination of electron transfer equilibria A(1-) + B = A + B(1-) in the gas phase, with a pulsed-electron high-pressure mass spectrometer, leads to ΔG10, ΔH10, and ΔS10 values.These can be converted into the free energy, enthalpy and entropy changes, ΔGa0(B), ΔHa0(B) and ΔSa0(B), for the reaction e + B = B(1-), since the corresponding values for the reference compounds A are known.Results were obtained for 18 substituted naphthalenes, anthracene and substituted anthracenes.The results are compared with some theoretical predictions and the corresponding reduction potentials in solution.Rate constants for 13 exoergic electron-transfer reactions were also measured.These were found to be close to the ADO collision rates.
- Heinis, Thomas,Chowdhury, Swapan,Kebarle, Paul
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p. 358 - 365
(2007/10/02)
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- The Addition-Elimination Mechanism in the Photonitration of Naphthalene by Tetranitromethane
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By the isolation and kinetic studies of an adduct (cis-1,4-dihydro-1-nitro-4-trinitromethylnaphthalene) from the photolysis of naphthalene-tetranitromethane in dichloromethane or acetonitrile, it is shown that the route to nitro substitution products proceeds via addition-elimination, the latter step being either thermal or base-catalysed.
- Eberson, Lennart,Hartshorn, Michael P.,Radner, Finn,Robinson, Ward T.
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p. 566 - 567
(2007/10/02)
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- Photochemical Nitration by Tetranitromethane. Part VI. Predominant Nitro/trinitromethyl Addition to Naphthalene in Dichloromethane and Acetonitrile
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The photochemical reaction between naphthalene and tetranitromethane in dichloromethane or acetonitrile gave predominantly (85-95percent) products of nitro/trinitromethyl addition to the aromatic system, namely cis- and trans-1-nitro-4-trinitromethyl-1,4-dihydronaphthalene and trans-2-nitro-1-trinitromethyl-1,2-dihydronaphthalene.A small amount of trans-2-hydroxy-1-trinitromethyl adduct was also formed, presumably originating from an initial nitrito/trinitromethyl adduct.The minor reaction pathway directly gave product(s) of nitro substitution, the ratio of 1- to 2-nitronaphthalene being high (25) in dichloromethane and in the beginning of the acetonitrile runs (up to ca. 40percent conversion).The temperature dependence of this process suggests that coupling between (naphthalene)cation radical and nitrogen dioxide is the major pathway leading directly to nitro products. 2-Nitronaphthalene, formed after long reaction periods in acetonitrile runs, was presumably formed via elimination of nitroform from the 1,2-adduct. cis-1-Nitro-4-trinitromethyl-1,4-dihydronaphthalene was isolated in pure form and shown to undergo facile base-catalysed elimination of nitroform in dichloromethane and acetonitrile to give 1-nitronaphthalene.It also underwent a slow spontaneous elimination in acetonitrile.It was stable under acidic conditions.GLC of the pure adduct gave exclusively 1-nitronaphthalene at a low injector-port temperature, whereas at higher temperatures a mixture of products was formed (naphthalene, 1- and 2-nitronaphthalene and 1-naphthonitrile).
- Eberson, Lennart,Hartshorn, Michael P.,Radner, Finn
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p. 1793 - 1798
(2007/10/02)
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- The Mechanism of Charge-transfer Nitration of Naphthalene
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Electrophilic (thermal) and charge-transfer (photochemical) nitration of naphthalene are effectively carried out in acetonitrile with various X-substituted N-nitropyridinium salts with X=4-MeO, H, 4-MeO2C and 2,6-Me2.Quantitative analyses indicate that both processes effect nuclear nitration to afford the same distribution of isomeric α- and β-nitronaphthalenes, together with the production of various amounts of (nitro-pyridine) adducts to naphthalene.Time-resolved (picosecond) spectroscopy identifies the naphthalene cation radical (NAPH) as the critical reactive intermediate in charge-transfer nitration.The subsequent disappearance of NAPH cation radical occurs by its combination with NO2 to form the isomeric (α/β) Wheland intermediates, which suffer competitive deprotonation (to yield the nitronaphthalenes) and nucleophilic addition (to produce the adducts).The relevance of such a charge-transfer mechanism to naphthalene nitration via the electrophilic (thermal) process is discussed.
- Kim, Eun K.,Bockman, T. Michael,Kochi, Jay K.
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p. 1879 - 1891
(2007/10/02)
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- Light-initiated and thermal nitration reactions during photolysis of naphthalene/tetranitromethane or 1-methoxynaphthalene/tetranitromethane in dichloromethane
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The photolysis of naphthalene or 1-methoxynaphthalene together with tetranitromethane in dichloromethane, using light with a cutoff at λ 2-promoted nitration (α/β ratio ca. 20). The adducts are formed by photochemical excitation of the CT complex between naphthalene and tetranitromethane, resulting in formation of the triad [ArH?+ NO2 (NO2)3C-] from which the observed chemistry develops by attack of trinitromethanide upon the radical cation. For 1-methoxynaphthalene, a representative of more highly reactive aromatics, the reaction is again photochemically initiated and again adducts seem to be responsible for the further development of thermal nitration reactions, apart from the NO2-induced reaction. Elimination of HNO2 from one of the 1,4-adducts induces a novel HNO2/tetranitromethane-dependent nitration process, shown separately to operate in the dark on reactive substrates. The aryltrinitromethane formed in this step is "hydrolyzed" to the corresponding carboxylic acid, 4-methoxy-1-naphthoic acid, under the anhydrous conditions prevailing during photolysis. Nitrous acid is a likely candidate as the proton source for this reaction. With an alcohol present, moderate yields (up to ≈50%) of alkyl 4-methoxy-1-naphthoates are obtained. From other adducts, nitro compounds are formed by elimination of nitroform. Trinitromethanide ion was shown to possess greatly differing reactivity (ratio >103) toward a model radical cation, tris(4-bromophenyl)aminium ion, in dichloromethane and acetonitrile, respectively.
- Eberson, Lennart,Radner, Finn
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p. 5825 - 5834
(2007/10/02)
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